Story highlights

Minnesota dentist says he relied on expertise of local guides "to ensure a legal hunt"

Zimbabwe officials say the American paid at least $50,000 to a safari guide

(CNN)Two men arrested in the death of Cecil the lion -- a case in which an American dentist has also been accused, unleashing a torrent of anger online -- were released Wednesday by a court in Zimbabwe on $1,000 bail each.

Theo Bronchorst, a professional hunter, and Honest Trymore Ndlovu, a landowner, both Zimbabweans, said through their attorney that they were innocent of poaching charges, which officials said could bring a sentence of 10 years in prison.

Zimbabwean authorities said that Walter J. Palmer, a dentist from Minnesota, paid at least $50,000 for the hunt.Palmer has said he relied on the expertise of local guides "to ensure a legal hunt."

But the lion that he and his local guides killed wasn't just any lion, according to Zimbabwean officials.

The hunters lured him out of the sanctuary of the park with a dead animal on top of a vehicle, the conservation group said.

Palmer, officials said, then shot the lion with a crossbow, a method for which he is known. But Cecil survived another 40 hours until the hunters tracked him down and shot him with a gun.

Walter J. Palmer, left, a U.S. hunter wanted in the killing of Zimbabwe's Cecil the lion, poses with a dead ram.

Cecil was skinned and beheaded, and the hunters tried to destroy the GPS collar that Cecil was wearing as part of research backed by Oxford University, the group said.

"I had no idea that the lion I took was a known, local favorite, was collared and part of a study until the end of the hunt," Palmer said Tuesday in a statement. "I relied on the expertise of my local professional guides to ensure a legal hunt."

Famed primatologist and conservationist Jane Goodall spoke about Cecil, saying, "He was not even killed outright, but suffered for hours before finally being shot with a bullet. . ... And this behavior is described as a 'sport.'"

"Only one good thing comes out of this," she said. "Thousands of people have read the story and have also been shocked. Their eyes opened to the dark side of human nature. Surely they will now be more prepared to fight for the protection of wild animals and the wild places where they live. Therein lies the hope."

In an email obtained by CNN affiliate WCCO, Palmer wrote a letter to his patients, saying, "I deeply regret that my pursuit of an activity I love and practice responsibly and legally resulted in the taking of this lion. That was never my intention."

Palmer said that the media, along with "a substantial number of comments and calls from people who are angered by this situation and by the practice of hunting in general," has disrupted his ability to see his patients.

"I apologize profoundly for this inconvenience and promise you that we will do our best to resume normal operations as soon as possible."

Dentist's enthusiasm for hunting with bow and arrow

Cecil's killing doesn't appear to be the first time Palmer has gotten into trouble while hunting.

A man by the same name and age, and from the same town, illegally killed a black bear in Wisconsin several years ago, according to court documents.

That individual pleaded guilty to making false statements knowingly to the U.S. Fish and Wildlife Service, and was sentenced to one year on probation and ordered to pay a fine of nearly $3,000, records show.

Palmer, right, poses with a dead black-tailed deer. The dentist said he "deeply" regrets killing Cecil the lion.

The Times article detailed Palmer's skill and enthusiasm for using archery rather than firearms to slay animals.

He is "said to be capable of skewering a playing card from 100 yards with his compound bow," it said, recounting his killing of a large elk with an arrow in Northern California.

Fears for Cecil's cubs

Cecil's death is likely to have a damaging effect on his pride, officials said.

"The saddest part of all is that, now that Cecil is dead, the next lion in the hierarchy, Jericho will most likely kill all Cecil's cubs so that he can insert his own bloodline into the females," the Zimbabwe Conservation Force said.

"This is standard procedure for lions," it warned.

Compounding the problem, "the females of the pride could die trying to defend those young," said Jeff Flocken, the North American regional director for the International Fund for Animal Welfare.

Calls for trophy hunting ban

The killing of Cecil has renewed calls among activists for a ban on trophy hunting of animals such as lions in Africa.

Photos:The world's critically endangered species

Photos:The world's critically endangered species

Black rhino – Poachers and hunters are responsible for the early decline of black rhino population. The world's animal population has halved in 40 years as humans put unsustainable demands on Earth, according to a 2014 report from the World Wide Fund for Nature.

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Hawksbill sea turtle – The existence of Hawksbill sea turtles have been traced back 100 million years. Now they are critically endangered, the WWF says.

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Mountain gorilla – As humans move more into the mountain gorillas' territory, the gorillas have been pushed farther up into the mountains, forcing them to endure dangerous and sometimes deadly conditions, the WWF report on the planet says.

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Amur leopard – Amur Leopard, a rare species of leopard living on the borders of Russia and China, was the winner of the 2013 WWF award dedicated to the positive evolution of an endangered species, but remains critically endangered.

South China tiger – The South China tiger is considered "functionally extinct," as it has not been sighted in the wild for more than 25 years.

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Sumatran elephant – Sumatran elephants come into conflict with humans due to the rapid expansion of palm oil plantations which destroy their habitat.

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Sumatran tiger – Sumatran tigers are the smallest surviving tiger species and are protected by law in Indonesia. But despite increased efforts in tiger conservation, they remain critically endangered.

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Photos:The world's critically endangered species

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Western lowland gorilla – Western lowland gorillas are critically endangered species. Because of poaching and disease, their numbers have declined by more than 60% over the last 20 to 25 years, according to the WWF's report.

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Yangtze finless porpoise – The population of Yangtze finless porpoises is declining rapidly. The freshwater dolphins are suffering due to pollution and hunting.

By early Wednesday, more than 210,000 people signed an online petition demanding "justice" for Cecil. The petition called on Zimbabwean President Robert Mugabe to stop issuing hunting permits to kill endangered animals.

African lion populations have fallen almost 60% over three decades, and as few as 32,000 of them remain in the wild, according to the International Fund for Animal Welfare.

Hunters argue that by paying big bucks to hunt specific animals with authorities' permission, they can help fund the preservation of endangered species.

Researchers studied effects of hunting on Cecil's park

"Studies have shown that with these big, lavish hunts, only 3% to 5% of the income from that hunt actually ends up for local people on the ground where the hunt happens," Flocken said.

"There are much better ways to earn this kind of money -- revenue from nature tourism, where the animal's not killed, brings in three to 15 times what's brought in from these trophy hunts in Africa," he said.

The Oxford University researchers who have studied the lions where Cecil lived found that trophy hunting just outside the national park had "an alarming impact on lion numbers and population structure within the park."

"Each removal of a male lion by hunters on the borders of the park created a 'territorial vacuum' which drew males from further inside the protected area into boundary areas, where they, too, became vulnerable to hunters," the university said.

A complete moratorium on trophy hunting around the park between 2005 and 2008 coincided with a 50% increase in the lion population there, the researchers noted.

Trophy hunting restarted in 2009 but with close monitoring by the Oxford research team, Zimbabwean authorities and other groups to ensure its impact on the lion population was sustainable.